Arthropod type: general characteristic, classification

Our planet is very replete with variouscreatures, many different animals and plants we exist. But in this paper we will examine in detail the type of arthropods. General characteristics of these living beings will also be presented in the article.

amount

It is the largest and richest type in the animal.the world. Representatives there are about a million species. Their number is one third of all living organisms of our planet, both living at a given time and extinct. Before we examine the question "General characteristics of the type of arthropods" (Grade 7 of the secondary school is obliged to acquaint children with its representatives), it is necessary to know that a large number of creatures still remain unexplored, their actual number could theoretically reach ten or more millions.

They are everywhere:in the seas, oceans, freshwater sources, on land. Based on which ecosystem has chosen a specific species, one can judge the evolution and food preferences. The type of arthropods, the general characteristics of which is our main task, is diverse; we suggest that the classification be considered for systematization.

Protection

We have already mentioned that the type has a largenumber of creatures, but, despite this diversity, they all have a relatively similar body structure. Considering the type of arthropods (general characteristics), we note a similar feature - an external rigid skeleton consisting of chitin. Some species have an exoskeleton containing lipids, proteins and calcium carbonate. This outdoor costume provides them with body protection and support. Also the walls of the shell fasten the muscles.

It is also important that all representatives are subject to moulting, this process occurs due to the fact that the exoskeleton is not growing, and during the growth of the animal a larger house is needed.

Body

The type of arthropods is rich and diverse.The general characteristic includes such a feature as segmentation. The whole body is divided into segments. Sometimes they grow together, in which case they are called tagmata, and the process is called tagmasis. One example is the accretion of a conjoined head, chest, and abdomen. Also, arthropods have processes with joints - this is where such a name comes from, literally translated as “jointed legs”.

Take the earliest and primitive arthropods,then each segment of their body was associated with only one pair of appendages. However, most species evolved, and limbs have changed, other structures have been formed, for example:

• mouth apparatus;
• antennae;
• reproductive organs and so on.

In arthropods, the appendages can be either branched or not branched.

Feelings, gas exchange, blood circulation

Many representatives have well-developed sense organs (paired faceted eyes), although some do not enjoy this privilege. Their circulatory system is open, has no blood vessels.

Gas exchange occurs in several ways:

• gills;
• trachea;
• lungs.

Most representatives of arthropods are dioecious, usually fertilization occurs internally, and eggs are laid.

Arthropod type: general characteristic, classification

These are symmetrical animals.It is also important to mention that they originate from ringed worms. If you analyze well, then you can notice the similarity in the structure. The only thing in the course of development and evolution first reached a high level of organization. Arthropods (general characteristics of the type, systematics and other issues will be consecrated in detail) are divided into the following main classes:

• crustaceans;
• arachnids;
• insects.

In turn, each class is divided into detachments.For example, among crustaceans they distinguish: branched, copepods and decapods. Spiders, mites and scorpions are referred to arachnids. And insects have a very large number of orders, such as:

• orthoptera;
• dragonflies;
• dipterans;
• beetles;
• hemiptera;
• hymenoptera;
• equal wings
• fleas and many others.

Consider each class separately.

Crustaceans

This is a fairly diverse class, numbering about forty thousand species. Mostly they can be found in the seas and freshwater bodies of water, but there are some who have mastered the land.

Although the type of arthropods (crustacean class, commonthe characteristics of which are considered in this section are very rich, but a number of similar features can be identified; for this, at the end of the paragraph we will provide a table that helps to systematize the knowledge gained.

Они ведут плавающий, ползающий или прикрепленный Lifestyle. Even parasites are found among them. As mentioned earlier, arthropods differ in segmentation of the body, they are in this class from ten to fifty.

Briefly consider the characteristic of a typicalrepresentative of this class, all known crayfish. From the name it is already becoming clear that it lives in freshwater bodies. His role in nature and for man is very large. Note that it is possible to distinguish even outwardly male and female.

Активность достигается в ночное время, питается it is exclusively vegetable food, eating both live and dead prey. The size of a mature individual is from fifteen centimeters or more, they moult once a year, in young animals this process is observed several times a year.

Like other representatives of arthropods,the circulatory system is open; the heart looks like a pentahedral bag and is attached to the back of the body. It is also important to know that the head and torso are connected. Tactile and olfactory feelings are sharp due to the long whiskers. The eyes are complex and attached to the flagella that compensates for the immobility of the head.

Type of arthropods, arachnid class: general characteristics

Так же как и предыдущий, очень богат, насчитывает more than thirty thousand species of living creatures, most of which live on land, but there are also representatives of secondary water. Like crustaceans, they have a cephalothorax, in addition to this there is an abdomen. Note that the segmentation is subject to change (some mites do not have a segmented body at all, for example, a dog).

The first segment of the body (cephalothorax) attaches six pairs of limbs to itself:

• Two pairs - legs.
• Four pairs - legs.

There are no extremities on the abdomen, but some representatives of this class have lung sacs, sex plates or spider warts.

Another distinctive feature of arachnids isouter layer consisting of lipoprotein, which protects the body from moisture loss. Most have poisonous and spider glands. As a rule, arachnids are predators, but a large group consists of parasites and herbivores. Breathing is done with the help of lung sacs or trachea, but in spiders with the help of these two organs. The organs of sight, touch, smell, and taste are fairly well developed, but for some ticks the sight is completely absent.

Fertilization occurs internally, there is a live birth in some species of mites and scorpions. Although this class is quite diverse, but the most important are such units as:

• Spiders
• Ticks.
• Scorpions

Insects

We present a table reflecting the main features of insects.

This is the least studied class, but no less significant compared to the others, it is poorly studied by science just because it is young.